Kitchen Mysteries_ Revealing the Science of Cooking Part 11

CONCENTRATION: The proportion of a molecule in a system. Also, the name of the operation that increases this proportion.

CONDUCTION: Constantly in motion, molecules transmit their energy by colliding with one another. That is how heat is spread by conduction. In an oven, for example, the interior of a roast is heated through conduction.

CONVECTION: The circulation of a fluid that appears, for example, when it is heated from below. Less dense than the other layers, the lower ones rise, pus.h.i.+ng the upper layers of fluid out of their way.

COPPER: A metal with red highlights that conducts heat very well, perfect for saucepans.

CREAM: An emulsion that forms naturally on the surface of milk when fat droplets gather and rise to the surface because they are less dense than the water. The cream we buy in grocery stores or supermarkets has generally been cultured with microorganisms that stabilize it but give it an acidity that the product drawn off the surface of milk does not possess.

CUL-DE-POULE: Literally, "a hen's backside"; this is a hemispherical copper bowl cooks use when beating egg whites. It is reserved for this use and cleaned with a clean rag soaked in vinegar or lemon juice.

D.

DEGLAZING: An operation that consists of recuperating the sapid and odorant molecules in the bottom of a pan by adding a liquid like bouillon, meat juices, or wine.

DENATURATION: Changing the structure of proteins; in other words, the protein chain folds back differently over itself.

DIFFUSION: The movement of molecules. A drop of coloring deposited in a gla.s.s of water is diluted because the molecules of the coloring diffuse in the water.

DIHYDROGEN SULFIDE: A foul-smelling molecule composed of one sulfur atom and two hydrogen atoms. It is released when hard-boiled eggs are cooked for too long.

DISTILLATION: A process supposedly invented by the Iranian doctor Avicenna in about the year 1000, though, in reality, it was probably used long before then. Distillation dissociates mixtures through successive evaporation of the const.i.tuents. When wine is heated, the ethyl alcohol escapes as vapor at 78C (172F), while the water does not boil until it reaches 100C (212F).

DISULFIDE BRIDGE: A bond between two sulfur atoms. These form especially between the amino acids called cysteines.

E.

EGG: Composed of three princ.i.p.al parts, the sh.e.l.l, the yolk, and the white. The yolk is composed of half water and half proteins and other surface-active molecules, such as lecithins. The white is a solution of proteins in water.

EMULSION: The dispersion of droplets of a liquid fatty substance in water or, conversely, of water in a liquid fatty substance (the structure depends on the respective proportions of water and fat). The stability is increased when the droplets are coated with surface-active molecules. If the proportions of an emulsion are altered, it can invert itself. In cooking, the result of such inversions is generally disastrous.

ENERGY: I have failed to find a good definition for this major concept in science, but it is always a good idea to a.n.a.lyze physical phenomena in terms of energy.

ENZYME: A protein possessing a catalytic action.

ETHYLENE: A gas that plays a part in the ripening of fruit. Certain fruits release more of it than others. That is the reason why bananas ripen quickly when they are put together in a fruit bowl with oranges.

F.

FATTY ACID: A long organic molecule in which one carbon atom of the structure bears an acid group COOH, called the carboxyl group.

FERMENTATION: A controlled transformation of a food involving microorganisms, yeasts for bread, yeasts and bacteria for wine, lactobacillus for sauerkraut.

FLOCCULATION: The regathering of droplets initially dispersed in an emulsion. It is also a preliminary step before coalescence.

FLOUR: A product obtained by grinding grains of wheat, rye, oats, corn, and so on.

FRUCTOSE: A sugar with a chemical structure that includes six carbon atoms.

FRYING: An operation that consists of immersing foods into very hot fat.

G.

GAS: The whole of molecules weakly bound to one another and moving around randomly within the entire volume available to them. Also, it is the punishment of those who eat indigestible food products.

GEL: A semisolid, three-dimensional network formed when a solution contains jelling molecules, that is, molecules capable of bonding to one another and to a great quant.i.ty of water.

GEL (OR JELL): As a verb, the formation of a gel, generally by lowering the temperature of a solution containing jelling molecules.

GELATIN: A substance with strong jelling properties obtained through the dissociation of collagen. When a gelatin solution cools, the gelatin molecules tend to bond to one another to form triple helixes, as in collagen.

GeNOISE: A sponge cake obtained by beating a mixture of whole eggs and sugar for a long time. It takes longer and is more difficult for the eggs to form stiff peaks since the whites are not beaten separately.

GLAZE: For the physicist, this is a thin coating of ice; for the cook, it is the jelled ma.s.s obtained by reducing a stock (which see).

GLIADINS: Insoluble proteins in flour.

GLOBULINS: Soluble proteins in flour. The name comes from the way they are folded back on themselves in the shape of globules.

GLUCIDES: Or, more simply, sugars. Their old name, carbohydrates, was given to them because these molecules have an overall composition of one carbon atom for one oxygen and two hydrogen atoms. They react with proteins when heated to form molecules that have color or delight the nostrils with their aroma.

GLUCOSE: A sugar with a structure that includes six carbon atoms. This is the "fuel" that living cells burn.

GLUTEN: In the presence of water, flour proteins form an elastic network that we call gluten. Try this experiment: knead flour and water for a long time; then hold the dough you obtain under running water; what remains is an elastic, insoluble ma.s.s, the gluten.

GLUTENINS: Insoluble proteins in flour.

GLYCEROL: This is the glycerin that you can find in a drugstore. It is present in wines, giving them sweetness and smoothness.

GOURMAND: A glutton with self-control, and this is why gourmands are good representatives of the world of culture.

GOURMET: A specialist in wines.

H.

HANGING PHEASANT: Contrary to what many believe, this is not a process of putrification, which would be dangerous for one's health. Hanging pheasant is like hanging venison. It must be done with an unplucked bird, which is suspended by its tail feathers for two to ten days, depending on weather conditions. It is said that the immortal Brillat-Savarin, author of The Physiology of Taste The Physiology of Taste and adviser to the French Supreme Court, always kept hung birds in his pockets, to the great discomfort of his colleagues. and adviser to the French Supreme Court, always kept hung birds in his pockets, to the great discomfort of his colleagues.

HOLLANDAISE: A sauce similar to bearnaise (which see) but differing from it because of the reduction, which contains no wine or shallots.

HYDROGEN: The first chemical element. Its atom is simply composed of a proton and an electron. Its ion, the hydrogen ion, is the proton deprived of its peripheral electron in the course of a chemical reaction. In solution, the hydrogen ion is surrounded by many water molecules; a solution in which it is abundant will be acid.

HYDROGEN BOND: A weak bond between a hydrogen atom and a neighboring atom, a donor of electrons (an oxygen atom, for example) in the same or another molecule.

HYDROLYSIS: A very important chemical process, as it generates amino acids when proteins are used as a substrate. These amino acids impart a wonderful taste to dishes.

HYDROPHILIC: A term used to describe a molecule that dissolves in water.

HYDROPHOBIC: A term used to describe a molecule that does not dissolve in water.

I.

ION: An atom that has gained or lost electrons. In water, ions surround themselves with water molecules.

J.

JAM: A flavorful gel (which see) always kept on the highest shelf in the pantry.

JELLY: A flavored gel.

L.

LACTOBACILLUS: A single-cell organism that releases lactic acid. This bacterium is found in sauerkraut or in bread dough left to ferment naturally (sourdough).

LECITHIN: A surface-active molecule found especially in egg yolk, but which has cousins in all cell membranes of plant or animal tissues.

LEAVENING AGENTS: Unlike yeasts, these are not microorganisms but mixtures of chemical compounds, such as baking powder or baking soda, capable of releasing a gas (often carbon dioxide) that makes food preparations rise. They are also called leavening powders.

LIPID: From the Greek, lipos lipos, fat. These molecules are defined by their insolubility in water. Food contains a wide variety of types of fat.

LIQUID: Formed when molecules make a whole less coherent than a solid but more coherent than a gas.

LUMPS: The disgrace of cooks.

M.

MAILLARD REACTIONS: Chemical reactions basic to cooking, since they take place between the sugars and proteins found everywhere in food. They produce compounds with odorant and color properties, like those in the crust of bread, beer, the crisp browned surface of meat, and so on.

MALTASE: An enzyme that decomposes the sugar called maltose.

Margarine: A soft, fatty substance made from many other substances, often vegetable in nature. Gastronomes often fault it for not having the subtle flavor of our best b.u.t.ters.

MAYONNAISE: This is an emulsion (which see), or a dispersion of oil droplets in water, the latter having been provided by egg yolk and possibly by vinegar or lemon juice. No mustard in mayonnaise, otherwise it is no longer mayonnaise but remoulade (please do not confuse hammer and screwdriver, cats and dogs, science and technology, or mayonnaise and remoulade!) MEAT: A muscular ma.s.s, composed of elongated cells, the muscle fibers, which sometimes reach twenty centimeters in length. Each fiber is wrapped in a sheath of collagenic tissue, and the sheathed fibers are gathered together in a bundle by other sheaths of collagen.

MERINGUE: A solidified foam obtained by baking stiffly beaten egg whites to which sugar has been added. Meringues must be baked gently at a low temperature.

MICELLE: A sphere formed by surface-active molecules; in water, for example, the hydrophobic tails of the surface-active molecules gather together, and the hydrophilic heads position themselves on the periphery, in contact with the water.

MICROWAVE: A wave similar to light, with a different wavelength. Microwaves are composed of an electrical field and a magnetic field; they prompt the alignment of molecules like water, where the distribution of the electrons is not uniform. Thus stimulated in one direction and then another in a very rapid rhythm, the water molecules become agitated and then agitate the surrounding molecules. This movement of molecules corresponds to an increase in temperature.

MOLECULE: An a.s.semblage of atoms linked by chemical bonds. Molecules are formed and transformed by chemical reactions. They are not altered during physical transformations of matter.

MOUSSE: Or foam, the distribution of air bubbles in a solution or a solid. Egg whites beaten into stiff peaks form a liquid foam; meringue is a solid foam.

MYOGLOBIN: One of the proteins responsible for the color in meat.

MYOSIN: One of the princ.i.p.al proteins in muscles, responsible for muscular contraction. When meat is cooked, the myosin coagulates.

N.

NITRATE: A salt in which one of the ions is nitrate, composed of one nitrogen atom and three oxygen atoms. Used in the salting process.

NITRITE: A salt in which one of the ions is nitrite, composed of one nitrogen atom and two oxygen atoms. Also used in the salting process.

O.

OLIGOSACCHARIDE: A molecule composed of a number of monosaccharides. In other words, a small sugar composed of a few elementary sugars.

OSMAZOME: According to Brillat-Savarin, this was the the taste "principle" in meat. The shortcomings of nineteenth-century chemical a.n.a.lysis misled the great gastronome. Meat's flavor results from the presence of a great number of molecules. As Valery said, "anything that is simple is false." taste "principle" in meat. The shortcomings of nineteenth-century chemical a.n.a.lysis misled the great gastronome. Meat's flavor results from the presence of a great number of molecules. As Valery said, "anything that is simple is false."

OSMOSIS: A phenomenon that results from the uneven distribution of molecules. To explain briefly, a system made up of many kinds of molecules is in balance when the concentration of each type of molecule is identical in all parts of the system. If a salt crystal, for example, is deposited on the surface of a cell, the water molecules leave the cell so that their concentration will be equal in the cell and in the salt crystal.

OVALb.u.mIN: One of the proteins in egg white.

OXYGEN: This is the gas that our red corpuscles transport from the lungs to all our cells. In a water molecule, an oxygen atom is bound to two hydrogen atoms.

P.

PAPAIN: One of the proteins present in fresh papaya juice. It reacts with other proteins by decomposing them.

PASTEURIZATION: The rapid heating of foods for the purpose of destroying the microorganisms that would spoil them.

PECTIN: A polymer present in plant cell walls. It forms the gel in jams.

PH: The unit of measure for acidity.

PHENOL: An organic molecule containing an aromatic ring of six carbon atoms, one of which is linked in particular to an alcohol (OH) group.

PHOSPHOLIPID: A lipid with one extremity that bears a hydrophilic phosphate group. Phospholipids are surfactants because of their hydrophilic part and their lipidic, hydrophobic part.

PHYSICS: The science of matter in general. Along with chemistry, it ought to be a help to cooks.

PIANO: A great chef's piano is his stovetop and work surface.

POLYMER: A large molecule formed by the linking of subunits called monomers. If you imagine a chain, the links would be the monomers.

PROTEIN: A chain in which the links are amino acids residues. In plant and animal organisms, these supple molecules fold over on themselves following specific patterns. By increasing the movements of atoms and various parts of the molecules, heat destroys the patterns natural to proteins. Thus we say that the proteins are denatured.

PUFF PASTRY: Obtained by six successive foldings of pastry dough into thirds. The result is 729 layers of dough separated by b.u.t.ter.

R.

REDUCTION: The process by which, through heating, the excess liquid in a dish, a sauce, or a garnish is evaporated. Reduction is fundamental in cooking. Not only does it give a preparation its final viscosity, but it is also often vital to the development of flavor and aroma. This is where physics and chemistry merge, the height of culinary alchemy.

ROUX: A pastelike preparation obtained by cooking flour or starch in a fatty substance. Diluted, it thickens the aqueous solution that is added to it because it provides starch granules that swell and release bulky amylose and amylopectin molecules.

S.

SABAYON: A delicious dessert obtained by mixing eggs (especially the yolks) and sugar and then adding an alcoholic liquid. Cooking it, after adding a pinch of flour, results in its thickening.